bool CCrypter::SetKeyFromPassphrase(const SecureString& strKeyData, const std::vector<unsigned char>& chSalt, const unsigned int nRounds, const unsigned int nDerivationMethod)
{
if (nRounds < 1 || chSalt.size() != WALLET_CRYPTO_SALT_SIZE)
return false;
int i = 0;
if (nDerivationMethod == 0)
{
i = EVP_BytesToKey(EVP_aes_256_cbc(), EVP_sha512(), &chSalt[0],
(unsigned char *)&strKeyData[0], strKeyData.size(), nRounds, chKey, chIV);
}
if (nDerivationMethod == 1)
{
// Passphrase conversion
uint256 scryptHash = scrypt_salted_multiround_hash((const void*)strKeyData.c_str(), strKeyData.size(), &chSalt[0], 8, nRounds);
i = EVP_BytesToKey(EVP_aes_256_cbc(), EVP_sha512(), &chSalt[0],
(unsigned char *)&scryptHash, sizeof scryptHash, nRounds, chKey, chIV);
OPENSSL_cleanse(&scryptHash, sizeof scryptHash);
}
if (i != (int)WALLET_CRYPTO_KEY_SIZE)
{
OPENSSL_cleanse(chKey, sizeof(chKey));
OPENSSL_cleanse(chIV, sizeof(chIV));
return false;
}
fKeySet = true;
return true;
}
int CCrypter::BytesToKeySHA512AES(const std::vector<unsigned char>& chSalt, const SecureString& strKeyData, int count, unsigned char *key,unsigned char *iv) const
{
// This mimics the behavior of openssl's EVP_BytesToKey with an aes256cbc
// cipher and sha512 message digest. Because sha512's output size (64b) is
// greater than the aes256 block size (16b) + aes256 key size (32b),
// there's no need to process more than once (D_0).
if(!count || !key || !iv)
return 0;
unsigned char buf[CSHA512::OUTPUT_SIZE];
CSHA512 di;
di.Write((const unsigned char*)strKeyData.c_str(), strKeyData.size());
di.Write(chSalt.data(), chSalt.size());
di.Finalize(buf);
for(int i = 0; i != count - 1; i++)
di.Reset().Write(buf, sizeof(buf)).Finalize(buf);
memcpy(key, buf, WALLET_CRYPTO_KEY_SIZE);
memcpy(iv, buf + WALLET_CRYPTO_KEY_SIZE, WALLET_CRYPTO_IV_SIZE);
memory_cleanse(buf, sizeof(buf));
return WALLET_CRYPTO_KEY_SIZE;
}
// passphrase must be at most 256 characters or code may crash
void CMnemonic::ToSeed(SecureString mnemonic, SecureString passphrase, SecureVector& seedRet)
{
SecureString ssSalt = SecureString("mnemonic") + passphrase;
SecureVector vchSalt(ssSalt.begin(), ssSalt.end());
seedRet.resize(64);
// int PKCS5_PBKDF2_HMAC(const char *pass, int passlen,
// const unsigned char *salt, int saltlen, int iter,
// const EVP_MD *digest,
// int keylen, unsigned char *out);
PKCS5_PBKDF2_HMAC(mnemonic.c_str(), mnemonic.size(), &vchSalt[0], vchSalt.size(), 2048, EVP_sha512(), 64, &seedRet[0]);
}
int __pass_cb(char *buf, int size, int rwflag, void *u) {
Key::PassphraseFunctor* pf = (Key::PassphraseFunctor*)u;
bool verify = (rwflag == 1);
SecureString ss = (*pf)(verify);
int len;
len = ss.size();
if (len <= 0) return 0;
// if too long, truncate
if (len > size) len = size;
memcpy(buf, ss.c_str(), len);
return len;
}